Characterization of Materials for Exhaust Systems under Combined Mechanical and Corrosive Environment 2013-01-2420

Corrosion resistance is an extremely important technical issue for long-term durability and reliability performance of exhaust components and systems. Failure mechanisms, such as corrosion, fatigue, corrosion-fatigue and stress corrosion cracking, have long been recognized as the principal degradation and failure mechanisms of vehicle components and systems under combined mechanical and corrosive environmental conditions. The combination of fluid flow, introduced by components such as advanced injectors, and corrosive environment leads to corrosion-erosion failure mechanism. These failure mechanisms are strongly material, environment, and loading dependent. How to characterize, screen, rank and select the materials in corrosion resistance is a big challenge posed to materials scientists and engineers.

In this paper, the common corrosion related failure mechanisms appearing in auto exhaust systems are reviewed first. Then, several approaches for accelerated corrosive resistance characterization under various environmental and loading conditions are introduced. Materials screening, ranking in corrosion resistance are also provided and discussed for several scenarios. Finally, the interaction or synergistic effect among multiple failure mechanisms are also introduced.